Decompression unit for equalizing an explosive air pressure

ABSTRACT

The invention relates to a decompression unit for equalizing an explosive air pressure between pressurized areas of an aircraft, which have different air pressure conditions and are separated by a wall structure. An air chamber, whose shape alters by contraction ( 1 ), is located inside an exterior zone of the cabin ( 6 ) and is subjected to an ambient air pressure (p 1 ), said chamber constituting the decompression unit in concrete terms. The wall of the air chamber ( 1 ) is perforated. The air chamber is mounted in the vicinity of the periphery of an air pressure equalization flap ( 2 ), which is fixed inside an air equalization cavity ( 9 ). Said air chamber is connected to a locking device ( 4 ), which likewise fixes the air pressure equalization flap in the air equalization cavity.

[0001] The invention relates to a decompression unit for equalizing anexplosive air pressure between pressurized areas of an aircraft withdifferent air pressure conditions. The different areas are separatedfrom one another by a wall structure.

[0002] Since the seventies of the 20^(th) century pressurized cabins ofcommercial aircraft are equipped with a system for the rapidequalization of the air pressure in the individual aircraft areas sothat a sudden pressure drop in the affected area cannot lead to afailure of flight critical structures or systems. A large capacitycommercial aircraft, a so-called wide body aircraft, has, as is known, alarge volume in the passenger cabin area above the floor as well as inthe freight area below the floor, whereby the venting cross-sectionalarea for the decompression air flow between these aircraft areas will beseveral times larger compared to the venting grid cross-section requiredfor the normal venting. configurations are known wherein respective airslot pressure equalization openings or pressure equalization flaps areused. These systems are, as a rule, installed in the floor covering orin the floor area of the respective aircraft areas in order to provideadditional air flow cross-section. A wide body commercial aircraftcomprises more than one hundred of these so-called decompression units,one of which unit is installed for each aircraft window area. Such airslot pressure equalization openings are easily installed, whereby,however, the carry-on baggage of an aircraft passenger or other onboardkitchen articles can easily block these pressure equalization openings.Thus, these openings are considered to be undesired lay-out elements.

[0003] In actual lay-outs for wide body aircraft actuating flaps areused for an enforced ventilation of the airstream entering behind thepressure equalization flap as a so-called air return flow duct of thenormal cabin venting. The individual flap will react in response to agiven pressure difference present between the air return flow duct onthe one hand and the low pressure level of the air below the cabin flooron the other hand. The flap will open in the direction outwardly, thatis in the direction of the lower air pressure. For this purpose thelocking bars which so far was locked to hold the flap within thestructure surrounding the flap, is released or unlocked, whereby thepressure equalization flap is pressed outwardly, namely it is lifted offthe surrounding structure so that now the excess cabin pressure canescape and a pressure equalization can take place. In this type ofdecompression unit only components are used having a fine adjustmentcharacteristic and a large surface area for achieving their purpose.These known constructions with pressure equalization flaps fordecompression purposes are uniformly hard to classify, whereby due totheir complicated construction additionally a respective effort andexpense must be taken into account for the maintenance and undesiredrepairs.

[0004] In view of the above it is the object of the invention to improvea decompression application as defined above in such a way that apressure equalization plate is equipped with a suitable mechanism whichcan also be retrofitted without a large effort and expense, whichmechanism holds the pressure equalization plate during normal flight andalso when an unintended loading or adjustment of the effective range dueto diverse air passenger loads occur, in the structure surrounding thepressure equalization plate. Thereby it is required (compared to airpassenger loads), that occurring low pressure loads do not cause theopening of the pressure equalization flap. However, the mechanism shallreact to suddenly occurring small cabin air pressure changes. During thenormal cruising flight including ascending and descending flight of anaircraft the mechanism shall be resistant to gradually changing airpressure conditions in the space of the respective aircraft area. Morespecifically, the mechanism shall not be sensitive to gradual smallchanges of the desired air pressure conditions. Additionally, themechanism shall be independent of the size and shape of the pressureequalization flap. Moreover the mechanism shall work reliably not usingexternal energy sources. Furthermore, the improved decompression deviceas compared to actual system layouts shall provide a contribution to aweight reduction as compared to decompression function units operatingsolely for the purpose of decompression.

[0005] The object is achieved by the features defined in claim 1. In thefurther claims suitable embodiments and modifications of these featuresare defined. The invention is described in an example embodiment withreference to the accompanying drawings which show:

[0006]FIG. 1 a decompression unit for the explosive air pressureequalization by a pressure equalization flap held in the wall structurewhen the air pressure ratio is equalized between pressurized areas of anaircraft;

[0007]FIG. 2 the deformed decompression unit of the pressureequalization flap which is still held in the wall structure according toFIG. 1 when the external pressure has dropped;

[0008]FIG. 3 the pressure equalization flap with the deformeddecompression unit according to FIG. 2 in the wall structure in its openstate;

[0009]FIG. 4 shows a plan view of the decompression unit divided intoseveral individual chambers; and

[0010]FIG. 5 is a side view of the decompression unit according to FIG.4, wherein the several individual chambers are connected in series.

[0011] To start with, it assumed that the decompression unit comprisesan air chamber 1, the inner space of which is divided into severalindividual chambers 11, 12, 13 and 14 for the reasons described belowwith reference to FIG. 4. The individual chambers are connected inseries with one another. The present air chamber 1 or the individualchambers 11, 12, 13 and 14 shown in FIG. 4 represent for the viewerrespective hollow bodies having a variable configuration. These chambersare made of a suitable material that is porous or perforated and isvariable in its shape. This porous or perforated material is made stiffin the plane of the chamber wall, but flexible in other directions. Itis suggested that textile woven material is used which is sufficientlyair permeable. Due to the given air permeability of the chamber wall orwalls the individual chamber will suck air under certain air pressureconditions prevailing outside the chamber wall. Further, the chamberwill change its shape or configuration in the above mentioned directionsby contraction. The air pressure conditions will be described in moredetail below.

[0012] The decompression unit shown in FIG. 1 relates to a single airchamber 1 having a flat body shape. The air chamber 1 made of a textilewoven fabric material comprises a plurality of perforations through thechamber wall. These perforations are shown. This also applies to theother chambers relative to FIGS. 4 and 5.

[0013] Each perforation comprises a defined, effective cross-sectionalarea. The effective perforation area is determined for each individualarea or for the entire area of the surface of the perforated chamberwall. The entire perforation surface area integrates several individualareas and is determined to assure a sufficient air permeability and thusa sufficient contraction of the air chamber 1 according to FIGS. 2 and 3and also of the working chambers 11, 12, 13 and 14 according to FIGS. 4and 5.

[0014] Referring again to FIG. 1 it is noted that the decompression unitas incorporated by the air chamber 1 for the explosive air pressureequalization is mounted near the periphery of an air pressureequalization flap 2 which is mounted in the structure surrounding theflap. The surrounding structure is formed by a wall structure 3 in whichthere is at least one pressure equalization opening 9 which opening isclosed by the air pressure equalization flap 2. This wall structure 3which is formed by a separation wall, separates two pressurized areasfrom each other. The pressurized areas have different air pressureconditions and relate, for example to a cabin inner space 7 and a space6 outside the cabin. Thereby, the lower flat surface area of the airchamber 1 rests substantially on the surface of the air pressureequalization flap 2 which faces toward the space 6 outside the cabin.The flat surface facing the flap 2 extends along the chamberlongitudinal axis 21 and is shown in its not yet contracted state. Theattachment of the air chamber 1 as shown in FIG. 1, is accomplished by aconnection element 5, 15 which is not expandable and is formed at thebody ends where the flattening ends. The free end of a first connectingelement 5 is secured either on the air pressure equalization flap 2itself or with a sufficient spacing on the wall structure 3 or on aspace element close to the flap 2 but not shown in the space 7 outsidethe cabin. (Note: space outside cabin 6 in FIG. 1). On the one hand, inpractice the air pressure equalization flap 2 is connected on one sideby a joint 8 or hinge positioned on the edge of the pressureequalization opening 9. Thus, the flap 2 is supported relative to thewall structure 3 such as a separation wall in a rotatable manner.Therefore, on the other hand, the flap 2 is generally secured at itsopposite free flap end, that is at the flap edge, to a locking mechanism4. Thus, this flap end is held in place by a locking bar of the lockingmechanism 4 constructed as a latching unit, in the wall structure 3surrounding the flap when the pressure equalization opening 9 is in itsclosed state as indicated by the arrow. It is now provided that the freeend of a nonexpandable second connection element 15 is connected withthe locking mechanism 4, in order to free the air pressure equalizationflap 2 out of its securing. This is achieved by contraction of the airchamber 1 which thereby changes its air chamber configuration in theabove mentioned directions thereby freeing the locking bar not shown. Itis mentioned additionally that the secured connecting elements 5 and 15may be installed with a certain biasing force which, however, does notimpair with the securement by the locking bar. the following thequestion will be answered how the present decompression utilization willperform the release of the air

[0015] In pressure equalization flap 2 out of the interlocking due tothe intended pressure equalization between aircraft areas positionednext to each other and dependent on the situation. The unlocking shallbe independent of the shape and size of the air pressure equalizationflap 2. The flap shall operate without an externally referencedprovision of aircraft internal energy sources.

[0016] Generally speaking, the space 6 outside the cabin 6 is exposed toan ambient air pressure p1 and the cabin inner space 7 is at a cabinpressure p2. According to FIG. 2 equalized air pressure conditions arepresent between these two aircraft areas which means that the ambientair pressure p1 is equal in its value to the cabin air pressure.

[0017] Contrary thereto, the situation according to FIG. 2, takes intoaccount unequalized pressure conditions between the two above mentionedaircraft areas. In this situation the ambient air pressure p1 in thespace 6 outside the cabin will have dropped by a differential airpressure value dp. According to the material characteristics of the airchamber 1 (and taking into account the above discussed generalconsiderations), the latter will change its body shape in response to asudden drop of the ambient pressure p1. With the pressure drop in thespace 6 outside the cabin, that is also in the surroundings of the airchamber 1, a reduced pressure will occur. As a result, a respective airvolume will be sucked through the perforations of the chamber wall intothe hollow space of the air chamber 1, whereupon the flexible material(fabric type) chamber wall will change its outer shape due to thefilling with air. More specifically due to the mentioned materialcharacteristic of the air chamber, the air chamber will change its shapeby contraction. Thus, when the air pressure surrounding the air chamber1 correspondingly drops so that it falls below the cabin air pressurep2, the air chamber 1 will change from its flat body shape that waspresent when there was pressure equalization between the pressures p1and p2, to a round shape having a prism type chamber cross-section dueto swelling. Thereby, the air chamber 1 will contract in the directionswhich extend rectangularly to the direction in which the chamber volumeincreases. On the other hand, the air chamber 1 will increase its sizedue to the air volume increase in the remaining chamber areas which donot contract in the direction extending across the chamber longitudinalaxis 21 to thereby increase its hollow space.

[0018]FIG. 3 shows to the person of ordinary skill the following. Theabove described operation according to FIG. 2 transmits an areadistributed pressure onto the surface of the air pressure equalizationflap 2 due to the contraction that is taking place with thesimultaneously occurring shape change in the air chamber 1 and due tothe contact of the flap 2 with the air chamber 1 with the surface areasof the air chamber 1 that changed their shape in the direction of thechamber longitudinal axis 21. As a result, a defined tension force isdeveloped which is transmitted through the connection elements 5 and 15,connected to the chamber, onto their further connection end areas.

[0019] The tension force that is transmitted through the firstconnection element 5 will not endanger the securement of the firstconnection element 5 on the air pressure equalization flap 2 or on thewall structure 3 or on a space element within the space 6 outside thecabin. The mentioned space element is positioned close to the airpressure equalization flap 2 or close to the air chamber 1. Contrarythereto the tension force transmitted through the second connectionelement 15 onto the locking mechanism 4 or on the latching unit will besufficient to loosen the locking bar in the direction of the arrow,whereby the air pressure equalization flap is released from its lockedstatus. As a result, the flap is opened into the space 6 outside thecabin by the cabin air pressure p2 effective on the backside surface ofthe flap 2. Since the locking bar is operated by the contraction of theair chamber 1 a pressure equalization is taking place between the twocabin areas through the now opened pressure equalization opening 9.

[0020]FIG. 4 shows a plan view of an embodiment of the air chamber 1shown in FIG. 1, whereby this air chamber embodiment corresponds to aconstruction of an air mattress. Thus, the hollow space or inner spaceof the air chamber 1 provided as a decompression unit, is divided intoseveral individual chambers 11, 12, 13 and 14, whereby the chambersubdivided hollow spaces are not in air communication with another. Asmentioned, the perforation of the chamber wall and the selection ofmaterial corresponds to the above described facts. Holes 22 are providedfor the securing or for the mechanical connection of this type of airchamber. These holes 22 pass through the cross-section of the lateralmargin. One hole 22 is positioned close to the individual chamber 11which is equipped with a smaller volume expansion. This one hole 22 isprovided for the connection to the locking mechanisms 4, more preciselyto the locking bar of the locking bar unit. The remaining hole 23 whichis positioned oppositely and close to an individual chamber 14 equippedwith a larger volume expansion, is provided for the connection to theair pressure equalization flap 2 or to the wall structure 3. It isassumed that a space element close to these elements is excluded. It isfurther shown in this Fig. by the arrows which indicate the direction ofcontraction of the decompression unit constructed as a multichamber airchamber. Thereby, the individual chambers 11, 12, 13 and 14 form amultichamber air chamber in order to optimize the force transmission orpositional change of this multichamber air chamber onto the air pressureequalization flap 2 and in correlation to the locking mechanism 4, moreprecisely to the locking bar of the locking bar unit. In this chamberstructure the individual chambers 11, 12, 13 and 14 form a certainnumber of discrete hollow spaces which, as mentioned are not incommunication with one another. A suggestion for the type of material tobe used in the multichamber air chamber is mentioned with reference toFIG. 4. The process of contraction of the multichamber air chamber takesplace in accordance with above described sample sequence of theindividual air chamber 1 with reference to FIGS. 1 to 3 so that thecontracting effect of the respective individual chambers 11, 12, 13 and14, namely the air chambers will take place for the intended purpose.Additionally, the attentive viewer of FIG. 4, taken in correlation withFIG. 5 will generally glean that one of the two outer chambers 11, 14has a clearly larger chamber cross-section in its contracted statecompared to the remaining individual chambers 12, 13. The chamber 20will be used as an air chamber container.

[0021]FIG. 5 shows a side view of the embodiment according to FIG. 4,whereby it is emphasized that in this embodiment no air connectionexists between and among the individual chambers 11, 12, 13 and 14. Dueto the expansion of the individual air chambers a contraction of theentire so-called air mattress takes place, whereby in accordance withthis illustration in comparison to a view of FIG. 4, a reduction of thestructural length A of the mattress body by the length B to thecontracted length C already occurred. Due to the sequential arrangementof the individual chambers 11, 12, 13 and 14, respectively 20, thecontracted length is larger than that of but one air chamber. Thatmeans, that the contraction velocity is larger with several air chambersconnected in series than in one air chamber.

[0022] Due to individual chambers 11, 12, 13 and 14 (air chambers) ofdifferent sizes, it is thus possible to realize different reactionpaths. In the same way the contraction reaction time is influenceable.

[0023] For the sake of completeness several useful modifications ofdescribed explosive decompression unit, as far as not yet described,will be indicated in order to make these useful for being put intoservice or under various operating conditions to be taken into account.These will be discussed in the following. The chamber is or chambers areintentionally so constructed that the air exits slowly and thereby thechamber does not swell, and

[0024] so that therefore the locking mechanism 4 or locking bar unitwill not be operated, so that the limited working medium volume is notexhausted, when during normal flight operation of the aircraft changesoccur in the level of the cabin air pressure p2 in the cabin interiorarea 7 and in the ambient air pressure p1 in the space 6 outside thecabin. These changes last, as a rule, for several minutes.

[0025] Depending on the degree of permeability, on the ambientconditions and on the required closed loop control, it is possible toachieve the required permeability characteristic in that, as mentioned,a porous fabric is used for the individual chamber or in that severalperforations are provided in the chamber wall.

[0026] The compression unit may be built from several individual airchambers 11 to 14 that work in sequence in order to amplify the change.The typical welding or adhesive bonding seam at the chamber marginprovides connections which, if necessary, may be reinforced by alamination and/or by eyelets.

[0027] It is suggested to produce the air chambers from suitablematerials having a long storage life, for example material that iscustomarily used in the aviation branch such as fabric material which isproduced in accordance with known production or manufacturing methodsfor making life vests, emergency chutes or air rafts or similarmaterials officially permitted. The porous material is similar to or asstrong as that of an airbag which are used in the car manufacturingindustry. A qualification for the aviation area may eventually benecessary.

[0028] The locking bars of the so-called locking bar unit shall be soconstructed that only a small energy supply is required for theunlocking or opening of the locking bar, whereby it is not absolutelynecessary that the locking bar unit after the unlocking of the airpressure equalization flap 2 is maintained opened. Therefore, it issuggested to use a flip lock or a bi-stable lock or simply merely anarresting snap lock for the locking.

[0029] A repeatable locking bar operating force (locking) will improvethe reliability of the present decompression unit in that an inadvertentlocking bar operation or locking is prevented in case the unit isintended for operation at low pressure differences.

[0030] Furthermore, referring to the construction and the function ofthe decompression unit, it is further added, as far as not yet clearlyemphasized, that the individual inflatable air aspirating air chamber 1relative to the other chambers, is made of the same textile wovenmaterial which is confirmed, as mentioned, to be stiff and rigid in thesubstantially flat plane of the chamber wall and has flexiblecharacteristics in the other directions. The body shape of the airchamber permits changing its body shape with a gaseous medium, such asair, by contraction for the intended purpose to vary its volume. The airchamber 1 and the other present chamber types operate under theprinciple according to which the surface area of the chamber remainseffectively constant so that the expansion force or respectively thepositional change of the chamber due to the pressure that is provided bythe medium, here air, is directly transformed into a contraction forceor length change at or near the pressure equalization flap 2. Thecontraction force or length change extends at about a right angle to thedirection of the original or first expansion.

[0031] Further, the decompression unit develops an expansion force dueto the following capability, namely the above mentioned change of thegeometric body proportions of the individual air chamber 1 or of thearrangement of individual chambers 11 to 14, respectively 20. Thesechambers may be connected either in series or in parallel or even in amixed connection due to the position of their connection possibilities.The expansion force causes the transmission of the contraction force orof the summed-up contraction forces to the air pressure equalizationflap 2 by changing its physical position. The summed-up contractionforces form a uniformly effective contraction force. It is the purposeof these measures that the force transmission to the air pressureequalization flap 2 is achieved without further components such aslevers or rod links.

[0032] In comparison to conventional products, the main advantages ofthe decompression unit for rationalizing the pressure equalizationbetween pressurized aircraft areas, are seen in that one will use anindependently working air volume in an efficient pressure container,that is the air chamber 1, which works independently of an air returnflow duct that is conventionally connected to the pressure container.Further, the material, the volume and the shape of the air chamber canbe optimized for the decompression sensitivity or the reliability,whereby the air chamber 1 will have a minimal size and a minimal weight.Besides, a small inertia and a rapid system reaction is achieved.Simplicity, low costs for the production, and during use, as well as ahigh reliability are further advantageous characteristics of the airchamber or air chambers that are worth mentioning. The present solutionworks independently of the shape and size of the pressure equalizationflap 2 or of the aircraft structure in which the flap 2 is installed.Thus, the present solution can be used in other aircraft types anddifferently equipped aircraft without the need for certain modificationsof respective components. The decompression unit can be separatelycertified, whereby all improvements which are not related to thedecompression can be made without expensive permitting activities forthe component: decompression to be tested.

[0033] A function testing for the certification or for the satisfactionof current air worthiness requirements can be finished with a smalltesting apparatus, namely a syringe without any substantial effort andexpense.

[0034] Finally, it is mentioned that compared to known decompressionapplications the use of the present decompression unit including itsmodified embodiment for the equalization of the air pressure betweenpressurized spaces for aviation applications, achieves a substantialweight, volume and complexity reduction including cost savings. Theapplication of the present solution is not limited to aircraftmanufacturing. Its use is always then beneficial when for certainsolutions the force transmissions of a contracting body due to thepressure of a stored medium, becomes sensible in order to achieve thebody position of another body by the force action. Thus, this fact willbe of special interest if one intends to produce a direct tension forcewithout a large effort and expense, whereby one can do without theintermediate use of other structural components such as levers or linkrods.

1. Decompression unit for the explosive air pressure equalizationbetween pressurized areas of an aircraft with differing air pressureconditions, wherein the areas are separated by a wall structure (3) inwhich there is at least one pressure equalization opening (9), whereinthe pressure equalization opening (9) is closed by an air pressureequalization flap (2), and wherein the latter is connected with alocking mechanism (4) secured to the wall structure (3), whereby thelocking mechanism (4) holds the air pressure equalization flap in thepressure equalization opening (9), characterized in that within a space(6) pressured by an ambient air pressure (p1) outside a cabin, there isarranged an air chamber (1) that changes itself by contraction and formsthe decompression unit and which has a perforated wall which is securedin the vicinity of the periphery of the air pressure equalization flap(2) and which is connected with the locking mechanism (4). 2.Decompression unit according to claim 1, characterized in that the airchamber (1) is a substantially flat body that extends along a chamberlongitudinal axis (21), said flat body having body ends at the ends ofthe flattening, at which ends a connection element is formed which isnot capable to expand, wherein a first connection element (5) is securedto the air pressure equalization flap (2) or to the wall structure (3)or to a space element close to the pressure equalization flap, andwherein a second connecting element (15) is connected with the lockingmechanism (4).
 3. Decompression unit according to claim 1, characterizedin that the inner space of the air chamber (1) is divided into severalindividual chambers (11, 12, 13, 14).
 4. Decompression unit according toone of the claims 1 to 3, characterized in that the air chamber (1) orthe individual chambers (11, 12, 13, 14) change their shape in responseto changing pressure conditions in such a way that the individualchamber, under the influence of a falling ambient air pressure (p1)which is below a cabin air pressure (p2) within a cabin inner area (7)that is separated or bulkheaded by the wall structure (3), has or havethe ability to change its or their substantially flat body shape due tothe contraction that starts at the body ends and travels toward the bodycenter, whereby the body shape in its end status when the cabin pressure(p2) is larger than the ambient pressure (p1), is a round swollen thickbody shape with a chamber cross-section resembling an ellipsis or abarrel resembling body shape.
 5. Decompression unit according to claim4, characterized in that the individual air chamber (1) or theindividual single chamber (11, 12, 13, 14) in its contracted endposition or state is arranged to lie with its outer chamber surface onthe flap surface of the air pressure equalization flap (2) that facestoward the cabin outer area (7), and a sufficient tension force of thetwo connecting elements (5, 15) is developed by the air chamber (1) orby the outer positioned individual chambers (11, 14) of the seriallyconnected individual chambers (11, 12, 13, 14) due to the chamber growthby contraction so that an opening or actuation of the locking mechanism(4) is achieved through the second connecting element (15). 6.Decompression unit according to claims 3 to 5, characterized in that oneof the outer positioned individual chambers (11, 14) has in itscontracted final state an enlarged chamber cross-section compared to theremaining individual chambers (12 and 13) and that it is used as airchamber container (20).
 7. Decompression unit according to claim 3,characterized in that the individual chambers (11, 12, 13, 14) areconnected in series without an air communication.